[Bug 12826] cpufreq driver do not expose all data and configuration to /sys

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http://bugzilla.kernel.org/show_bug.cgi?id=12826





------- Comment #18 from uzytkownik2@xxxxxxxxx  2009-03-07 03:10 -------
On Sat, 2009-03-07 at 04:38 +0000, Matthew Garrett wrote:
> On Fri, Mar 06, 2009 at 08:27:56PM -0800, Andrew Morton wrote:
> > On Sat, 7 Mar 2009 03:45:12 +0000 Matthew Garrett <mjg@xxxxxxxxxx> wrote:
> > 
> > > The low-level cpufreq drivers have no idea whether a speed request 
> > > originated from userspace or the kernel, so we'd need to either special 
> > > case p4-clockmod in the core or add an argument that everything other 
> > > than p4-clockmod ignores. Or we could figure out why this computer 
> > > overheats and fix that bug.
> > 
> > Please stop deleting and then ignoring everything I say.
> > 
> > The ONLY way of fully repairing this regression is to restore the sysfs
> > files, and their 2.6.28 functionality.
> 
> Resulting in computers that run slower and consume more power. "My 
> script that does something stupid now gives an error" isn't a 
> regression. "My computer now overheats" is a bug that was being hidden 
> in the first place. Why don't we just fix that bug?
> 

AFAIU the system from Dave Jones post I've found today p4-clockmod is
suppose to work with ACPI evenets. 
I've found out that:
# cat /proc/acpi/thermal_zone/THM0/polling_frequency 
<polling disabled>
# cat /proc/acpi/thermal_zone/THM0/state 
state:                   ok
# cat /proc/acpi/thermal_zone/THM0/temperature 
temperature:             81 C
# cat /proc/acpi/thermal_zone/THM0/trip_points 
critical (S5):           99 C
passive:                 95 C: tc1=5 tc2=4 tsp=600 devices= CPU

The problem is that it seems that the system halts at about 95 C - in
moment when cooling should be applied. This might be an ACPI/ibm_acpi
bug.

Also in one comment[1] it have been mentioned that on Celeron M, which
lacks SpeedStep[2] and C-states[3], there are power savings as
p4-clockmod is enabled. So maybe p4-clockmod should be used fully only
for Celeron M (with appropriate renaming and description) - and only
Celeron M - as cpufreq backend and for rest it should warn/not expose
the sysfs interface? 

Regards

[1] http://www.codemonkey.org.uk/2009/01/18/forthcoming-p4clockmod/
[2] Confirmed on
http://en.wikipedia.org/w/index.php?title=Celeron&oldid=272955598#Mobile_Celeron_and_Celeron_M
[3] Powertop however reports different C-states on my computer. Maybe it
varies from core to core.


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